A communication system can be seen as a facility that enables communication sessions between two or more entities such as a communication device and/or other nodes associated with the communication system. Subscribers, such as the users or end-users, to a communication system may be offered and provided numerous services, such as two-way or multi-way calls, data communication or multimedia services or simply an access to a network, such as the Internet. The services may be offered by an operator of a network of the communication system or by an external service provider.
Examples of communication systems may include fixed line communication systems, such as a public switched telephone network (PSTN), wireless communication systems, such as a public land mobile network (PLMN), e.g. global system for mobile communications (GSM), general packet radio service (GPRS), universal mobile telecommunications system (UMTS), other wireless networks, such as a wireless local area network (WLAN), and so on, and/or other communication networks, such as an Internet Protocol (IP) network and/or other packet switched data networks. Various communication systems may simultaneously be concerned in a connection.
Any appropriate communication device may be used for accessing a communication system. Examples of communication devices may comprise, but are not limited to, wireless devices, e.g. user equipment (UE), a mobile station (MS), a cellular phone, a personal digital assistant (PDA) or the like, or other terminals, such as a personal computer (PC), or any other equipment operable according to a suitable network protocol, such as a wireless applications protocol (WAP) or a hypertext transfer protocol (HTTP). The communication device may support, in addition to call and network access functions, other services, such as short message service (SMS), multimedia message service (MMS), electronic mail (email), Web service interface (WSI) messaging and voice mail.
A user of a wireless communication device may access a communication network via a radio access network (RAN), which is typically controlled by an appropriate controller network element, such as radio network controller (RNC). Examples of radio access networks may comprise the UMTS terrestrial radio access network (UTRAN) and the GSM/EDGE radio access network (GERAN).
Application servers operating beyond the Gi interface may provide data transfer services to an individual as point-to-point or one-to-one services or group(s) of individuals as point-to-multipoint or one-to-many services. Such groups may be large in number of individuals comprised in the group. In the GPRS, the Gi may be defined as the interface between a gateway GPRS support node (GGSN) and an external public data network (PDN), such as the Internet. Thus, the application server operates beyond cellular networks and has no visibility to cellular specific addressing. An application server may use Uniform Resource Identifiers (URIs) and IP addresses to address members of a group. When distributing a data stream to a group, an application server may multiply the incoming data stream to obtain copies of the data stream for each member of the group. The application server may then send the copies of the data stream via the Gi interface to a cellular network and leave a responsibility of the data transfer thereafter to the cellular network.
The solution described above may work well when groups are relatively small or physically scattered. However, as a size of the group becomes greater or when a lot of members are located in a small geographical area, problems may arise. It is then more likely that too many members are located in close proximity with each other and might have to be served by a single transceiver network element using the same physical radio resources for many members of the group. A particular cell may be congested and data may not be delivered to all members. In addition to congestion problem in some particular cells, also other problems may be faced as many identical data streams are conveyed to many recipients within a single cellular network.
The way of transferring group data described above may not be efficient from a system resource point of view. In particular, with a great number of participants it may also appear to be impossible.
A direct one-to-one and one-to-many voice communication system named as Push to talk over Cellular (PoC) has been developed. The PoC service is based on half-duplex Voice over IP (VoIP) technology in cellular networks, e.g. the GSM/GPRS network. The PoC uses an “always-on” connection, which allows a subscriber to have a direct access to the service after the subscription to the service without additional measures, such as dial-up. The PoC enables a subscriber to listen to group traffic. Call can be started to both individuals and groups with a simple action, such as a push of a key. The call connection is established automatically and the receiver does not need to answer the call. In the network, a controlling server takes care of session management and floor control, such as multiplying the speech (i.e. the VoIP) for all members of a group.
Furthermore, a cellular system may include a multimedia broadcast/multicast service (MBMS) server, which is able to broadcast or multicast information to multiple participants over a geographical area. An MBMS server is not able to form groups, but provides information of different multicasting groups to participants. It is a responsibility of the participants to subscribe and join to a multicast service in order to receive the data. A reference architecture to support MBMS is defined by the Third Generation Partnership Project (3GPP) in TS 23.246 V.6.3.0 (2004-06) “Technical Specification Group services and System Aspects; Multimedia Broadcast/Multicast Service (MBMS); architecture and functional description (Release 6)”, FIG. 1.
It might be desired to distribute data to a number of participants within an environment that comprises both application servers and broadcast/multicast service servers, such as MBMS servers, within a cellular network system. However, linking the application servers situated beyond the cellular network and the MBMS servers situated in the cellular network may be difficult.
It shall be appreciated that these issues are not limited to any particular communication environment, but may occur in any appropriate communication system.